Supersonic intake for a jet engine



A ril 18, 1967 R H 3,314,437

SUPERSONIC INTAKE FOR A JET ENGINE Filed July 16, 1965 United States Patntspf 3,314,437 SUPERSONIC INTAKE FOR A JET ENGINE Malcolm Roy Pike, Woodthorpe, Nottingham, Engiand, assignor to Rolls-Royce Limited, Derby, England, a company of Great Britain Filed July 16, 1965, Ser. No. 472,494 (Jiaims priority, appiication Great Britain, Aug. 5, 1964, 31,901/64 3 Claims. (Cl. 137-151) This invention concerns a supersonic intake for a jet engine.

According to the present invention there is provided a supersonic air intake for a jet propulsion engine comprising an outer casing, a fixed structure mounted in said casing and defining with the outer casing an annular air intake duct therebetween, the fixed structure having a surface disposed adjacent the upstream end of the outer casing, a coaxially disposed spike mounted in the fixed structure for axial movement with respect thereto, power means for effecting axial movement of the spike, the maximum diameter of the spike being substantially smaller than that of the said surface, the spike extending forwardly of the said surface and having an outer tip which, during supersonic flight, defines with the said surface a substantially conical flow separation zone.

The intake may produce a normal shock, the said surface lying substantially in the plane of the normal shock.

Alternatively, the intake may produce an internal shock system extending across the said intake duct.

The fixed structure may comprise a casing having an interior which is open to ram air, the said surface being an annular surface at the upstream end of the inner casing.

The said casing may be provided with one or more doors which may be opened to permit air from the interior of the inner casing to flow into the said intake duct.

The invention also comprises a jet engine provided with a supersonic intake as set forth above.

The invention is illustrated, merely 'by way of example, in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic side view of a jet engine provided with a supersonic intake according to the present invention, and

FIGURE 2 is a broken away cross sectional view of the intake of the engine of FIGURE 1.

In FIGURE 1 there is shown a supersonic gas turbine jet engine having an external compression intake 24.

The engine 10 has an outer casing 25 within which is mounted a fixed centre body 34 (see FIGURE 2).

In FIGURE 2 there is a detailed view of a supersonic external-internal compression intake 24 provided with an outer casing 25 having a fixed inner casing 26 mounted therein. The inner casing 26 is supported from the outer casing 25 by a plurality of angularly spaced apart struts 27. An intake duct 30 is defined between the outer casing 25 and the inner casing 26.

The inner casing 26 has an interior 31 which is open to ram air, the inner casing 26 having an annular surface 32 which is disposed adjacent the upstream end of the outer casing 25. r

Mounted Within the inner casing 26 and supported therefrom by a plurality of angularly spaced apart struts 33 is a centre body 34.

Mounted for axial movement within the centre body 34 3,314,437 Patented Apr. 18, 1967 is a coaxially disposed spike 36 whose maximum diameter is substantially less than that of the surface 32.

The spike 36 extends forwardly of the surface 32 and has an outer tip 40 which during supersonic flight forms with the surface '32 a substantially conical flow separation zone 41.

The end of the spike 36 remote from the outer tip 40 is formed with a piston '21 which is slidabiy mounted in a cylinder 22. The cylinder 22 is provided with a hydraulic or pneumatic pressure fluid by way of a conduit 23. It will thus be appreciated that the spike 36 may be disposed in a number of different axial positions, whereby to permit variation of the apex angle of the flow separation zone 41 and thus to match the intake 24 to a large range of supersonic speeds.

The intake 24 has internal shocks 42, 43 which extend across the intake duct 30.

The inner casing 26 is provided with doors 44 which may be opened to permit air from the interior 31 of the inner casing '26 to flow into the intake duct 30 so as to supplement intake throat area and reduce intake pressure losses at transonic speeds and for take off. Thus, at such low speeds the speed of air fiow is reduced and therefore, no shocks 42, 43 occur, and the intake duct is then not large enough for the engine. The provision of the doors 44, however, enables further air to be admitted to the engine.

I claim:

1. A supersonic air intake for a jet propulsion engine comprising an outer casing, a fixed structure mounted in said outer casing and defining with the outer casing an annular air intake duct therebetween, the said structure incorporating an inner casing which has an interior open to ram air and which has an annular surface at the upstream end thereof, means provided in said inner casing for permitting air from the interior of said inner casing to flow into said intake duct, a coaxially disposed spike mounted in said fixed structure for axial movement with respect thereto, power means for effecting axial movement of the spike, the maximum diameter of the spike being substantially smaller than that of the said surface, the spike extending forwardly of the said surface and having an outer tip which, during supersonic flight, defines with the said surface a substantially conical flow separation zone.

2. A supersonic air intake as claimed in claim 1 in which the intake produces an internal shock wave system extending across the said intake duct.

3. A supersonic air intake as claimed in claim 1 in which the said means for permitting air from the interior of said inner casing to flow into said intake duct comprises at least one door which may be selectively opened and closed respectively to permit and prevent the air flow firom the interior of the inner easing into the said intake uct.

References Cited by the Examiner UNITED STATES PATENTS 3,008,667 11/1961 Dean 6035.66 3,028,731 4/1962 Drake 60-356 

1. A SUPERSONIC AIR INTAKE FOR A JET PROPULSION ENGINE COMPRISING AN OUTER CASING, A FIXED STRUCTURE MOUNTED IN SAID OUTER CASING AND DEFINING WITH THE OUTER CASING AN ANNULAR AIR INTAKE DUCT THEREBETWEEN, THE SAID STRUCTURE INCORPORATING AN INNER CASING WHICH HAS AN INTERIOR OPEN TO RAM AIR AND WHICH HAS AN ANNULAR SURFACE AT THE UPSTREAM END THEREOF, MEANS PROVIDED IN SAID INNER CASING FOR PERMITTING AIR FROM THE INTERIOR OF SAID INNER CASING TO FLOW INTO SAID INTAKE DUCT, A COAXIALLY DISPOSED SPIKE MOUNTED IN SAID FIXED STRUCTURE FOR AXIAL MOVEMENT WITH RESPECT THERETO, POWER MEANS FOR EFFECTING AXIAL MOVEMENT OF THE SPIKE, THE MAXIMUM DIAMETER OF THE SPIKE BEING SUBSTANTIALLY SMALLER THAN THAT OF THE SAID SURFACE, THE SPIKE EXTENDING FORWARDLY OF THE SAID SURFACE AND HAVING AN OUTER TIP WHICH, DURING SUPERSONIC FLIGHT, DEFINES WITH THE SAID SURFACE A SUBSTANTIALLY CONICAL FLOW SEPARATION ZONE. 